Add support for dynamic field filtering (ability to ignore field at r…

…untime) to generate custom csv tables from a single struct

Update actions to use Go1.16

Adjust tests for older Go versions

Support inline tag in Header function

Fix panic while encoding uninitialized ptr on interface field

Adjust for Go1.11

Fix Header and EncodeHeader type recognition

Type was incorrectly recognized in cases where value was
wrapped in additional interfaces

Decoder should store its own copy of the header

Add AutoHeader field to Encoder

Improve Decoder.Header documentation